Tens of thousands of babies are born each year with congenital heart defects that restrict blood flow from the heart, threatening their lives from the moment of birth. Millions of older Americans suffer from blood flow problems as a result of arteriosclerosis, a plaque buildup that can lead to stroke or heart attack. Doctors have a range of corrective surgeries to choose from to treat these patients. But how can surgeons tell which is the best one for a particular patient's vascular system?

In the past, it has been more of an art than a science. Doctors could diagnose a problem and gather empirical data but did not have the tools to anticipate how a patient would respond to surgery. Charles Taylor's research, however, could soon inject a healthy dose of scientific method into these decisions. Taylor, his research team, and his clinical collaborators, including Christopher K. Zarins, MD, Frank Arko, MD, and Jeffrey A. Feinstein, MD, have created software called ASPIRE—Advanced Surgical Planning Interactive Research Environment—that allows physicians to perform surgeries in cyberspace before going into the operating room. Using voluminous data collected from extensive patient MRIs (magnetic resonance imaging) and distilling it into 3-D images on a monitor, ASPIRE can predict how a particular patient's body would react to each procedure. With ASPIRE, a vascular surgeon or cardiologist could tinker with 10 possible scenarios, experimenting with various arterial bypasses, artificial arteries, and intravascular treatments such as angioplasty and stenting to correct blood flow, to determine which would create the best outcome. This ability to predict a patient's response will profoundly change the way surgery is done. "We want to transform medicine from a diagnostic and empirical method to a predictive one, where we will see how surgery will affect real patients," Taylor says.

A truly interdisciplinary researcher, Taylor holds appointments in mechanical engineering and surgery and, by courtesy, pediatrics, and is a founding faculty member of the bioengineering department. His training focused on computational mechanics, a prerequisite for the huge computational task that is ASPIRE—up to 50 million blood vessels may be included in the modeling process. Taylor began developing the computer algorithms behind ASPIRE, which now operates on a 128-processor Silicon Graphics supercomputer in the Clark Center, as a Stanford graduate student.

His research team also relies on the equipment at Stanford's Lucas Center for Magnetic Resonance Imaging. "It's the best place to do MRIs in the world," he says. Taylor has improvements in mind, however: He is striving to transform the way blood flow is measured by high-powered imaging systems. Typical MRIs are done with a patient lying flat; images show blood flow at rest. Many patients, however, experience problems only during physical activity. In response, Taylor and his research group have created a first-of-its-kind MRI-compatible bicycle that allows them to capture images of arteries during exercise.

Taylor's recent focus has been on a congenital heart problem called Tetralogy of Fallot, a pulmonary artery restriction and ventricular defect that affects approximately 2,000 babies each year in the United States. He has been working closely in this effort with Dr. Feinstein, pediatric cardiologist at Stanford. "Pediatric cardiologists have a saying, 'No flow, no grow.' In this condition, there is preferential blood flow to one lung, so little development of the other," Taylor says. If the condition is untreated, death or lifelong problems result. ASPIRE has shown that surgery is most useful in infancy, because later on—once lung development is already stunted—surgery may not be able to correct the problem. Taylor's work could help doctors better time and plan surgical intervention and prevent unnecessary surgeries. "This will revolutionize pediatric cardiology," a National Institutes of Health (NIH) reviewer commented on Taylor's work.

Currently, Taylor is conducting retrospective studies on patients who have undergone surgery, testing ASPIRE against real cases. He hopes that in another few years, surgeons and cardiologists will be able to use the software to accurately predict surgical results and better plan their interventions. The response from physicians has been very positive. Taylor looks forward to installing ASPIRE in the vascular surgery planning suite that will be part of Stanford's forthcoming Center for Simulation in Medicine. It's a first step toward offering an invaluable tool to surgeons at Stanford and, eventually, around the world.